This invention relates to a hood which is mounted to the tip of an insertion tube of an endoscope.
Generally, the hood has a cylindrical wall surrounding the end surface of the insertion tube. A suction channel is provided in the insertion tube, which opens at an end surface of the insertion tube. The suction opening is located in a cavity surrounded by the cylindrical wall of the hood.
In order to remove the mucous membrane, an operator inserts the insertion tube into the human body so that the hood abuts the mucous membrane. Then, the operator performs a suction (via the suction opening). Since the suction opening is located in the cavity surrounded by the hood, the mucous membrane is sucked in the cavity so that the sucked mucous membrane forms a polyp. The operator cuts the polyp by means of a snare inserted through the suction channel.
During these process, the operator observes the mucous membrane through a view window provided to the tip of the insertion tube. Generally, the view window and the suction opening are provided on the same end surface of the insertion tube and similarly surrounded by the cylindrical hood.
However, when the suction is performed, the sucked mucous membrane reaches the vicinity of the view window, which may interfere with the view of the operator. With this, it is difficult for the operator to observe the mucous membrane well.